Climbing outside also allows him to have variety. A rock gym has the same rocks all the time. Outside there are different mountains to climb.

"Each climb has a different feel," Mulherin said. "Inside is repetitive."

As a student, Mulherin finds autumn does not allow as many opportunities to go outside. In the summer, he would spend four days a week rock climbing. Now he only can go once a week.

Rock climbing is something that can be safe, if a person knows what to do and uses equipment such as a bouldering pad.

"It has a lot to do with experience and knowing limits," Mulherin said.

One of the most important things to learn is how to fall safely. He said a climber can feel when a fall is coming, so it is important to look down to make sure the fall will not be on the person's back.

"A lot of people struggle with control of a fall," Mulherin said. "It's kind of dangerous if you don't know what you're doing."